If you'd like a 4 lane computer system for your track for under $100 dollars then please read on.
I found these at http://www.dontronics-shop.com/
They are Duinomite boards by Olimex (based on the Maximite by Geoff Graham), they have a mono VGA output, PS2 keyboard input, 26 pin IO port, MicroSD card socket, plus other stuff we don't need.
The one on the left is the Duinomite Mini and it retails for $33.35. On the right is the Duinomite Mega which retails for $50.08. After a quick perusal of the specs I thought these would be perfect for an ultra budget slot racing system. Either board will do the job but I purchased the Mega because it has a more tolerant power requirement, 9v to 30v, whereas the Mini requires 5v regulated, any more and the smoke escapes.
Also there is a pretty box available for the Mega for $16.65, and here it is -
I didn't buy the box because this is supposed to be an Ultra Budget project and I'd already splurged on the bigger board.
Upon arrival of the board I scrounged up an old PS2 keyboard and an LED monitor and went to work. After checking the IO port specs I made up a simple test board with 4 buttons and 4 LEDs and started on the software. It took longer to make the test board than to write the software, so be gentle with criticism please – here's how stage 1 looks
It's pretty basic at the moment but it provides lap counting and timing and displays the best lap time and the last 9 lap times for each lane. Function keys 1 to 4 reset the laps and times on the relevent lanes and the space bar turns the track power on and off. I've set it up with 4 outputs for individual control of the lanes and have already started on the qualifying and race programs although they are much more complex and will be a "spare time" job. It would take very little work to add single lane lap races to the current software but I'll make up a decent test rig with buzzer and lights first.
Software can be downloaded here – http://johnsonsystem…1/DSoftware.txt
If you're still interested here are some specs.
The board uses a 32 bit PIC chip running at 80MHz which handles all functions and runs a basic interpreter.
The basic interpreter can run about 30,000 lines of code per second.
The board boots into a basic prompt unless it finds a file named "AUTORUN.BAS" on either it's internal drive or the SD card then it will run that.
Lap counter inputs are handled by an interrupt on IO pin change and timing when checked against a know good source is accurate to +/- 1ms plus rounding errors, so say +/- 2ms
Video resolution is 480 x 432 Mono (that's black and white only)
The screen title and lane names can be easily changed in the software.
The software requires MMBasic 3.1 which allows for 12 IO lines which I've allocated thus -
4 Inputs – Lap Counters – Interrupt on change either low to high or high to low (easily changed with 1 number in the software)
4 Outputs – Track Relays – Digital IO
1 Output – track On/Off indicator – probably use a SPDT relay to drive red/green LEDs or lights
1 Output – Buzzer – the board has a speaker connector but not all monitors have speakers
1 Input – Track Call Button
1 IO spare – I had an idea for this but I've forgotten what it was. Old age is a b!tch.
For the rest of the software I intend to start with a qualifying program and a round robin race program to take up to 50 entries. This will fit into the devices memory without problems. Bells and whistles will be added as needed and possible.
I think this is a worthwhile project for people with small tracks and/or budgets so if anyone is interested and wants more info please post questions on this thread.